8-14
DSP56309UM/D MOTOROLA
Serial Communication Interface (SCI)
SCI Programming Model
until the middle of the second bit transmitted after the external clock starts. Gating the
external clock off after the first bit has been transmitted delays TDRE indefinitely.
In asynchronous mode, the TDRE flag is not set immediately after a word is transferred
from the STX or STXA to the transmit shift register nor when the word first begins to be
shifted out. TDRE is set two cycles of the 16
´
clock after the start bitÑ that is, two
16
´
clock cycles into the transmission time of the first data bit.
8.3.2.3
SSR Receive Data Register Full (RDRF) Bit 2
The RDRF bit is set when a valid character is transferred to the SCI Receive Data Register
from the SCI receive shift register (regardless of the error bits condition). RDRF is
cleared when the SCI receive data register is read or by a hardware RESET signal,
software RESET instruction, SCI individual reset, or STOP instruction.
8.3.2.4
SSR Idle Line Flag (IDLE) Bit 3
IDLE is set when 10 (or 11) consecutive 1s are received. IDLE is cleared by a start-bit
detection. The IDLE status bit represents the status of the receive line. The transition of
IDLE from 0 to 1 can cause an IDLE interrupt (ILIE). IDLE is cleared by a hardware
RESET signal, software RESET instruction, SCI individual reset, or STOP instruction.
8.3.2.5
SSR Overrun Error Flag (OR) Bit 4
The OR flag bit is set when a byte is ready to be transferred from the receive shift register
to the receive data register (SRX) that is already full (RDRF = 1). The receive shift register
data is not transferred to the SRX. The OR flag indicates that character(s) in the received
data stream may have been lost. The only valid data is located in the SRX. OR is cleared
when the SCI Status Register is read, followed by a read of SRX. The OR bit clears the FE
and PE bitsÑthat is, an overrun error has higher priority than FE or PE. OR is cleared by
a hardware RESET signal, software RESET instruction, SCI individual reset, or STOP
instruction.
8.3.2.6
SSR Parity Error (PE) Bit 5
In the 11-bit asynchronous modes, the PE bit is set when an incorrect parity bit has been
detected in the received character. It is set simultaneously with RDRF for the byte which
contains the parity errorÑthat is, when the received word is transferred to the SRX. If PE
is set, further data transfer into the SRX is not inhibited. PE is cleared when the SCI
status register is read, followed by a read of SRX. PE is also cleared by a hardware
RESET signal, software RESET instruction, SCI individual reset, or STOP instruction. In
10-bit asynchronous mode, 11-bit multidrop mode, and 8-bit synchronous mode, the PE
bit is always cleared since there is no parity bit in these modes. If the byte received
causes both parity and overrun errors, the SCI receiver recognizes only the overrun
error.
Summary of Contents for DSP56309
Page 25: ...xxii DSP56309UM D MOTOROLA Figure D 25 Port E Registers PCRE PRRE PDRE D 39 ...
Page 30: ...MOTOROLA DSP56309UM D 1 1 SECTION 1 DSP56309 OVERVIEW ...
Page 47: ...1 18 DSP56309UM D MOTOROLA DSP56309 Overview DSP56309 Architecture Overview ...
Page 48: ...MOTOROLA DSP56309UM D 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Page 85: ...2 38 DSP56309UM D MOTOROLA Signal Connection Descriptions OnCE JTAG Interface ...
Page 86: ...MOTOROLA DSP56309UM D 3 1 SECTION 3 MEMORY CONFIGURATION ...
Page 104: ...MOTOROLA DSP56309UM D 4 1 SECTION 4 CORE CONFIGURATION ...
Page 124: ...MOTOROLA DSP56309UM D 5 1 SECTION 5 GENERAL PURPOSE I O ...
Page 125: ...5 2 DSP56309UM D MOTOROLA General Purpose I O 5 1 INTRODUCTION 5 3 5 2 PROGRAMMING MODEL 5 3 ...
Page 128: ...MOTOROLA DSP56309UM D 6 1 SECTION 6 HOST INTERFACE HI08 ...
Page 166: ...MOTOROLA DSP56309UM D 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Page 212: ...MOTOROLA DSP56309UM D 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Page 241: ...8 30 DSP56309UM D MOTOROLA Serial Communication Interface SCI GPIO Signals and Registers ...
Page 242: ...MOTOROLA DSP56309UM D 9 1 SECTION 9 TRIPLE TIMER MODULE ...
Page 269: ...9 28 DSP56309UM D MOTOROLA Triple Timer Module Timer Operational Modes ...
Page 270: ...MOTOROLA DSP56309UM D 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Page 302: ...MOTOROLA DSP56309UM D 11 1 SECTION 11 JTAG PORT ...
Page 369: ...C 22 DSP56309UM D MOTOROLA DSP56309 BSDL Listing ...
Page 370: ...MOTOROLA DSP56309UM D D 1 APPENDIX D PROGRAMMING REFERENCE ...
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